Theoretical Studies of Zone Plates Monolithically Integrated with Sensors.
Final rept. 1 Aug 71-31 Jul 72,
INVENTORS AND INVESTORS INC WILLIAMSTOWN MASS
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The intensity distribution of radiation focussed by zone plate optics has been analyzed and the radiation flux on a sensor area centered about the optical axis computed. It is found that sensor response to a Lorentzian beam distribution depends substantially on the ratio of sensor radius to the product of the aperture radius and the spectral half width. Response of an axially located disk-shaped sensor to an oblique incident beam is computed. Combinations of a zone plate with a phase filter to produce an annular image are described, and application to spectral separation of a beam comprising two distinct wavelengths of suitable ratio is suggested. Integrated zone plate sensor configurations are proposed with emphasis on increasing the focal length by multiple reflections on the wafer surfaces. Numerical examples are computed for incident radiation of 1.15 micron wavelength using a Schottky barrier sensor on silicon. Structures to achieve both suppression of reflection losses and phase compensation are suggested. Insertion gains by at least an order of magnitude appear feasible for microsensors. Author